Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2006270903 PROBLEM TO BE SOLVED: With the delay sum BF of the conventional filter design method (BF), processing can be easily performed only with phase, but when the beam is wide, the peak direction can not be guaranteed in the case of a sphere or unequally spaced array The side lobes were getting bigger. SOLUTION: A coefficient of beam forming (BF) is redesigned according to an input to realize high resolution beam forming (BF), and beam forming (BF) can be performed with any microphone arrangement including a spherical array etc. Further, weights are calculated based on the intensity distribution obtained by manipulating the beam direction of beam forming (BF) according to equation 9, and beam forming (BF) is redesigned according to equation 10. [Selected figure] Figure 1 Nonlinear beamforming with arbitrarily arranged microphone array [0001] The present invention relates to a method of designing a filter which forms a directional characteristic by arranging a plurality of microphone arrays in an arbitrary space and combining the output signals of the plurality of microphones. [0002] Conventionally, a method of recording a sound by providing a plurality of sound sensors with a wide range of microphones (see Patent Document 1) and a search apparatus using a spherical array transceiver (see Patent Document 2) have been disclosed. A method of forming a directional characteristic by combining a plurality of microphone signals through a filter has already been proposed. 04-05-2019 1 [0003] And, a recording system (hereinafter referred to as SBM) realized by a microphone on a sphere baffle has an advantage that the reflection and diffraction due to the microphone and its supporting part can be reduced by embedding the microphone and its supporting part inside the sphere. Although a method for forming a target directional characteristic has been proposed, the filter design method used here is such that the relationship between the parameter value such as the step size and the directional characteristic to be obtained is not clear because adaptive processing is used. . [0004] Conventionally, control of directivity characteristics by a plurality of microphones is performed as shown in FIG. 1 by setting N microphone signals X n (ω), n = 1, 2,. . . , N through a filter of transfer characteristics Gn (ω) and processed so as to obtain a recorded signal Y (ω) having directional characteristics, the distance r, azimuth angle θ, sound source X of elevation angle ( Assuming that the transfer function from ω) to microphone n is Hr, θ, ψ, n, (ω), the directivity characteristic D (r, θ, 含 む) including the distance direction in this processing is given by the following equation 15 It is a thing. [0005] [0006] Next, subscripts m (m = 1, 2,. In M), the following equation 16 is obtained. [0007] Number 16 ｄ＝Ｈｇ 04-05-2019 2 [0008] In this case, d is a directional characteristic vector, H is a transfer function matrix, g is a filter vector, and T is a transposed matrix, and the following equation 17 is obtained. [0009] [0010] Then, as for the conventional filter design method not including adaptive processing, there is delay sum beamforming (hereinafter BF), and if the filter gk in the target direction k is designed by the following equation 18, the phase that cancels out the transmission phase delay It becomes a filter with rotation, and * represents a complex conjugate. [0011] [0012] Next, when the filter gk in the target direction k of the weighted delay sum BF is designed as + with a pseudo inverse matrix and H with a Hermitian operator (complex conjugate transpose) according to the following Eq. 19, each delay sum BF Of the filters with a gain proportional to the transmission rate to the microphone, the gain in the direction k is 1 and the norm | gk | <2> is the smallest, and | hm | is constant depending on the direction | Dm | <1 (m ≠ k), and the peak is in the direction k, and in general, it is robust against fluctuation but has a wide directivity of the side rope. [0013] [0014] Next, a filter is designed to set the gain in the target direction k of the BF with NULL control to 1 and form NULL (gain 0) for non-target directions of N-1 or less, and the number of non-target directions is L , Gku is designed by the following equation 20, assuming that the direction is ul (l = 1, 2,..., L). [0015] 04-05-2019 3 [0016] Then, in the case of L (> N-1), the pseudo-inverse of the equation (20) can be calculated by the inverse matrix, and if the non-purpose direction is appropriately selected, the siderope from the delay sum BF at a particularly low frequency. Can form a directional characteristic in which the [0017] Furthermore, in LSE control BF, a filter that has a gain in the target direction k and keeps the gain low with respect to the non-target direction of L = N−1 is designed. 1 for the target direction and 0 for the non-target direction, but a filter of least square error (LSE) is designed, and generally the gain in the target direction decreases when L is increased, in this case in the target direction The weight w> 1 is added and the design can be relaxed by designing as the following equation 21. If the non-target direction is appropriately selected, the side rope can be suppressed to be low compared to the NULL control BF. [0018] [0019] JP, 2002-48867, A JP, 2000-162308, A [0020] The delay sum BF of the conventional filter design method (BF) can be easily processed only with the phase, but the beam is wide and the peak direction can not be guaranteed in the case of a sphere or an uneven array The side lobe becomes large, and the weighted delay sum BF is strong against the transfer function fluctuation, but the beam is wide and the side lobe becomes large. Furthermore, in the BF with NULL control Although the direction of the side lobe can be set to 0, only the number of microphones -1 can be set to 0, and the side lobe becomes large between the positions set to 0. Furthermore, in the LSE control BF, Although the side lobes in multiple directions can be made smaller, the height of the main beam is lowered, the gain in the target direction is not guaranteed, and additionally, the peak position is not guaranteed either. [0021] In view of the above problems, the present invention is optimal based on each criterion in beamforming (BF) in which the side rope (SL) is minimized in the LSE criterion and the Min-Max criterion as a result of intensive research, so the main lobe ( Although it is impossible to further reduce the side rope (SL) while keeping the ML) within a certain width, high resolution 04-05-2019 4 beamforming (BF) is required for applications such as sound source search, and the claims Nonlinear beamforming by the microphone array of arbitrary arrangement described in 1 goes beyond the framework of linear processing, redesigns the coefficient of beamforming (BF) according to the input, and realizes high resolution beamforming (BF). , Beam array (BF) with any microphone arrangement including spherical array etc. [0022] Furthermore, in the non-linear beamforming by the microphone array in an arbitrary arrangement according to claim 2, in the beamforming (BF) using the equation 9 according to claim 1, when the intensity distribution of the sound source is unknown, the beamforming (BF) It is optimal because it minimizes the expected value of the contribution (noise) of the output from the non-target direction, but when the intensity distribution is known, the noise itself is added by adding a weight proportional to the intensity. This can minimize the total noise by controlling the gain in the non-target direction smaller by a strong noise source, and the intensity distribution is often unknown in practice. Weights are calculated based on the intensity distribution obtained by manipulating the beam direction of beam forming (BF) according to equation 9, and beam forming (BF) is reestablished according to equation 10. And it performs, is similar to the general adaptive microphone array, any of the microphone array becomes available, based beamforming (BF) is one that may even not be NULL type. [0023] The non-linear beamforming by the microphone array of arbitrary arrangement of the present invention redesigns the filter coefficient of beamforming (BF) according to the input signal, thereby achieving high resolution and low resolution beyond the framework of linear fixed beamforming (BF) It is a realization of the beam forming (BF) of the side rope. [0024] The non-linear beamforming by an arbitrary arrangement of microphone arrays according to the present invention relates to a method of designing a filter for forming directional characteristics by arranging a plurality of phone arrays in an arbitrary space and combining them through output signals of the plurality of microphones. The beam forming (BF), which controls twodimensional directivity using SMA (Spherical Microphone Array) in which 31 microphones are embedded in a sphere of 130 mm in radius, generates a sound source by scanning the beam direction. Fig. 2 shows the results for a point source with the same intensity and phase at a frequency of 1000 Hz as (θ, () = (0, 0) and (60, 0). Delay sum, (b) is the root mean square minimum, (c) is beamforming (BF) with nonlinear optimization In (a), two sound sources can not be separated, and one sound source appears. In (b), a horizontally long sound source appears, and although the degree of separation is improved, it can not be said that it is sufficient. In c), the 04-05-2019 5 sound source can be completely recognized as two sound sources, and as for SL, (c) is small compared to (b), and SL can be reduced while narrowing the width of ML. [0025] The present invention will be described in detail with reference to the drawings of an embodiment of nonlinear beamforming by an arbitrary arrangement of microphone arrays according to the present invention. FIG. 1 shows microphone directivity characteristics of the embodiments of nonlinear beamforming by an arbitrary arrangement of microphone arrays of the present invention. FIG. 2 is an explanatory diagram showing a processing system, and FIG. 2 is a weighted delay sum, (b) is a root mean square minimum, and (c) is a non-linear beamforming embodiment according to the present invention. It is explanatory drawing showing the beam forming (BF) by optimization. [0026] That is, as shown in FIG. 1, nonlinear beamforming by an arbitrary arrangement of microphone arrays according to claim 1 of the present invention arranges a plurality of microphone arrays on an arbitrary space and outputs signals from the plurality of microphones. Is a method of designing a filter that forms a directional characteristic by combining them. [0027] Then, N microphones Mic. 1 to Mic. Signals X n (ω) from n, n = 1, 2,. . . , N through a filter of transfer characteristics Gn (ω) and processed so as to obtain a recorded signal Y (ω) having directional characteristics. [0028] Next, directional characteristics D (r, θ, including distance directions where the transfer function from the sound source X (ω) from the elevation angle r to the microphone n is Hr, θ, ψ, n (ω) ψ) is the following equation 22. [0029] [0030] Then, the directions of the directions separated in the target range are subscripted m (m = 1, 2, ... 04-05-2019 6 When expressed as M), the equation 22 is represented by the equations 23 and 24. [0031] Further, assuming a directivity characteristic vector d, a transfer function matrix H, and a filter vector g, the following equation 23 is obtained. Number 23 ｄ＝Ｈｇ [0032] Furthermore, T can be expressed by the following equation 24 when expressed as a transposed matrix. [0033] [0034] Then, a filter gk in which the gain is 1 in the target direction k and the peak in the vicinity of the target direction coincides with the target direction is defined as a solution of the following equation 25: drhk, dθhk, dψhk, in equation 25 Is a vector whose elements are the differential values at Hr, θ, ψ, n, (ω). [0035] [0036] This solution is generally infinite with N> 4 and is given by the following equation 26. [0037] 04-05-2019 7 [0038] Here, gk is a solution satisfying the above equation 25, y is an arbitrary vector, and Z is a matrix consisting of independent vectors spanning the null space of Hk. [0039] <img class = "EMIRef" id = "200753787-00000013" /> where Z is the singular value decomposition of Hk Hk = U <1> SV <H> and the column vector of V corresponding to singular value 0 Is obtained as [0040] [0041] Next, when the gain u in the non-target direction is expressed by the equation 26, the following equation 28 is obtained. [0042] [0043] Here, u is a directional characteristic vector in the non-target direction, U is a transfer function matrix in the non-target direction, and is given by the following equation 29. [0044] [0045] <img class = "EMIRef" id = "200753787-000017" /> It is obtained by the equation 30. [0046] [0047] <img class = "EMIRef" id = "200753787-000019" /> The diagonal matrix W is obtained by finding a solution according to the following equation 31: 04-05-2019 8 [0048] [0049] <img class = "EMIRef" id = "200753787-000021" /> Substituting to find gk. [0050] Furthermore, in the non-linear beamforming by the arbitrary microphone array according to claim 2 of the present invention, each of the non-linear beamformings using the arbitrary microphone array according to claim 1 was beamformed using the equation 31 Assuming that the matrix including the filter coefficients in the direction is Equation 32 and the input signal vector is Equation 33, the sound source distribution s estimated from Equation 31 can be calculated by Equation 34 using s = Gx. [0051] [0052] Number 33 ｘ＝［Ｘ１Ｘ２… ＸＮ］<Ｔ> [0053] Number 34 ｓ＝［ｓ１ｓ２… ｓＭ］<Ｔ> [0054] Then, the weight Wm in the non-target direction can be calculated by the following equation 35. 04-05-2019 9 [0055] Number 35 wm = | sm | + σ [0056] <img class = "EMIRef" id = "200753787-000023" /> [0057] In the beamforming by microphones using indefinite terms according to the present invention, a plurality of microphones are buried on the surface of a spherical baffle, and a filter is formed to form directional characteristics by synthesizing through output signals of the plurality of microphones. In beam forming (BF) where the side rope (SL) is the smallest in the LSE standard and the Min-Max standard, the side rope (SL) is optimal based on each standard, so the main lobe (ML) remains within a certain width. Although it is impossible to further reduce the rope (SL), in applications such as sound source search, it provides high resolution beamforming (BF). [0058] FIG. 1 is an explanatory view showing a directivity characteristic processing system of a microphone of an embodiment of nonlinear beam forming by an arbitrary arrangement of microphone arrays according to the present invention. Fig. 2 shows weighted delay sums (a) of the embodiments of nonlinear beamforming with microphone arrays of arbitrary arrangement according to the present invention, (b) mean square minimum, (c) beamforming (BF) by nonlinear optimization. FIG. 04-05-2019 10

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